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Fermi Level Pinning Induced by Doping in Air Stable n-Type Organic Semiconductor

Sharma, S and Ghosh, S and Ahmed, T and Ray, S and Islam, S and Salzner, U and Ghosh, A and Seki, S and Patil, S (2020) Fermi Level Pinning Induced by Doping in Air Stable n-Type Organic Semiconductor. In: ACS Applied Electronic Materials, 2 (1). pp. 66-73.

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Official URL: https://doi.org/10.1021/acsaelm.9b00742


Doping of organic semiconductors enhances the performance of optoelectronic devices. Although p-type doping is well studied and successfully deployed in optoelectronic devices, air stable n-type doping was still elusive. We succeeded with n-type doping of organic semiconductors using molecular dopant N-DMBI under ambient conditions. Strikingly, n-type doping accounts for a gigantic increase of the photoconductivity of doped thin films. Electrical and optical properties of the n-doped molecular semiconductor were investigated by temperature dependent conductivity, electron paramagnetic resonance (EPR), and flash-photolysis time-resolved microwave conductivity (FP-TRMC) measurements. A significant reduction and saturation in activation energy with increasing doping level clearly suggests the formation of an impurity band and enhancement in carrier density. Computational studies reveal the formation of a charge transfer complex mediated by hydrogen abstraction as the rate-determining step for the doping mechanism. The colossal enhancement of photoconductivity induced by n-doping is a significant step toward optoelectronic devices made of molecular semiconductors.

Item Type: Journal Article
Publication: ACS Applied Electronic Materials
Publisher: American Chemical Society
Additional Information: The copyright for this article belongs to the Author.
Keywords: Activation energy; Charge transfer; Electron spin resonance spectroscopy; Fermi level; Optical properties; Optoelectronic devices; Organic semiconductor materials; Paramagnetic resonance; Photoconductivity; Photolysis, Charge transfer complex; Computational studies; Electrical and optical properties; Electron paramagnetic resonances (EPR); Molecular semiconductors; N-type organic semiconductor; Temperature-dependent conductivity; Time-resolved microwave conductivities, Semiconductor doping
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited: 04 Jan 2023 10:16
Last Modified: 04 Jan 2023 10:16
URI: https://eprints.iisc.ac.in/id/eprint/79464

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